Improving the accuracy of automatic broiler weighing by image analysis

Flock managers of broilers need on-line information on their weight, uniformity and growth in order to evaluate feed conversion efficiency, occurrence of disease problems and animal welfare. Determining broiler body weight in a continuous manner is done today by one or more portable platform balances in the broiler house. However, the accuracy of the measurements from commercial available balances is still doubtful, especially at the end of the growing period. It was found from literature and field data that heavier broilers visited automatic weighing platforms less frequently at the end of the production cycle, resulting in a systematic under estimation of the average body weight. The objective of the study presented here was to provide a method that allows improved estimation of the average body weight of a group of broilers by combining automatic weighing platforms with image analysis. The new system consists of a camera mounted above a weighing platform, providing a top view of animals on and around the weighing platform in an area of about 2.3 m by 2.3 m. The top view images of the birds are used to correct for the bias of results from the weighing platform. The relation between the actual weight and the area of the birds is used to estimate the body weight of all animals within the frame of the camera. In an experiment over three fattening periods in three different experimental broiler houses, the new method was evaluated against manual weightings every week as a reference. From this analysis it was concluded that the combination of image analysis and automatic weighing provided a better estimate of the actual average body weight of the animals (5% error at the last day of the fattening period) compared to the readings of the automatic weighing only (14.1% error).